When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?

The question is incomplete as it does not have the options which are:

A) relay molecule

B) transducer

C) signal molecule

D) response molecule

C) signal molecule

Explanation:

The transmission of signals in the neurons takes place in the form of electrical energy and chemical energy. The signals get transmitted in the form of electrical signals inside the neurons but when the signals have to be passed on to the next neuron on the pathway then the electrical signals get converted into the chemical signals.

The electrical signals cause the release of the chemical signals molecules called neurotransmitter from the synaptic vesicles in the presynaptic neuron and also opens the gated ion channels at the terminal. The neurotransmitter thus acts as a signal molecule in the transmission of a signal through neurons.

Thus,  C) signal molecule  is the correct answer.